In this chapter, we got the chance to use ArrayList and enum. We also got to see how we can avoid using complicated math by utilizing the Android Matrix class.

Possibly the most important lesson from this chapter is how we saw that encapsulating and abstracting parts of our code to specific relevant classes helps to keep our code manageable.

The remaining two chapters will show how we can continually improve the structure of our code to increase the complexity and depth of our games (and other apps) without losing control of the code's clarity.

We will explore the topic of design patterns which is the art of using reusable existing solutions to make our code better and solve problems that arise when making games or other applications that would otherwise overwhelm us with their complexity. We will also be coding our first Java interfaces as part of exploring these patterns.

And don't worry, there will be plenty more game related lessons in the final two projects, including parallax scrolling backgrounds, particle explosions, multi-level explorable game worlds using a camera, persisting the high score, multiple, thinking enemy types and more.